Michael A. Boogaard David A. Johnson Dorance C. Brege Ronald J. Scholefield R. Wayne Westman Brian E. Stephens Terry D. Bills 2003 <p><span>It has long been known that the toxicity of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is influenced by chemical and physical properties of water. As the pH, conductivity, and alkalinity of water increase, greater concentrations of TFM are required to kill sea lamprey (</span><i>Petromyzon marinus</i><span>) larvae. Consequently, the concentration of TFM required for effective treatment varies among streams. Brown trout (</span><i>Salmo trutta</i><span>) and sea lamprey larvae were exposed to a series of TFM concentrations in a continuous-flow diluter for 12 h. Twenty five exposures were conducted at various water alkalinities and pHs that treatment personnel encounter during lampricide treatments. Survival/mortality data were analyzed for lampricide concentrations that produced 50 and 99.9% mortality (LC</span>₅₀<span>&nbsp;and LC</span>_99.9<span>) for sea lamprey larvae and 25 and 50% mortality (LC</span>₂₅<span>&nbsp;and LC</span>₅₀<span>) for brown trout. Linear regression analyses were performed for each set of tests for each selected alkalinity by comparing the 12-h post exposure LC</span>_99.9<span>&nbsp;sea lamprey data and LC</span>₂₅<span>&nbsp;brown trout data at each pH. Mortality data from on-site toxicity tests conducted by lampricide control personnel were compared to predicted values from the pH/alkalinity prediction model. Of the 31 tests examined, 27 resulted in the LC</span>₁₀₀<span>s (lowest TFM concentration where 100% mortality of sea lamprey was observed after 12 h of exposure) falling within 0.2 mg/L of the predicted sea lamprey minimum lethal (LC</span>_99.9<span>) range. The pH/alkalinity prediction model provides managers with an operational tool that reduces the amount of TFM required for effective treatment while minimizing the impact on non-target organisms.</span></p> application/pdf 10.1016/S0380-1330(03)70512-7 en Elsevier Development of a pH/alkalinity treatment model for applications of the lampricide TFM to streams tributary to the Great Lakes article